A string trimmer (“weed whacker”) is a handheld device which uses a flexible line (“trimmer string”) to cut grass and other vegetation close to objects such as trees or pavement.
Typically, weed whackers comprise a cutting head at the end of a long shaft, and a handle. A trigger on the handle controls the speed of the cutting head containing trimmer string. The weed whacker may be powered by an internal combustion engine, an electric motor or a battery. Cutting is performed by the trimmer string which becomes stiff and extends horizontally outward as a result of centripetal forces when the cutting head rotates. The faster the cutting head rotates, the stiffer the trimmer string becomes. The cutting head often includes a safety shield on the user side and a rotating hub, or spool.
Many users find weed whackers difficult to operate and inefficient. Often, trimmer string must be hand-wound onto a spool before use. During use, the trimmer string may break off and the user may need to release additional trimmer string to replace the spent portion. Trimmer string may also become tangled or may break apart inside the safety shield. Trimmer string is often inadequate to cut thick vegetation and a user must switch between multiple gardening tools. Gardening often requires saw blades for cutting thick vegetation and earth tilling functions which are not available in ordinary weed whackers.